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Results for “CELL MEMBRANE PERMEABILITY”

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At least 19 recordsLinked to original sources
PubMedDate not supplied

Heat-induced alterations in cell membrane permeability and cell inactivation of transformed mouse fibroblasts.

Hyperthermia, has recently been extended in many permutations as a modality of anticancer treatment, but the mechanisms underlying heat-induced cell inactivation are poorly understood. In this study, the role of the cell permeability barrier in the process of heat cytotoxicity are examined. Changes in cell membrane permeability were determined by following the efflux of normally impermeant metabolites, e.g. nucleotides, in cultures of Swiss mouse 3T3 cells, and their transformed derivatives, 3T6 cells. The increase in cell membrane permeability as a function of temperature and exposure duration was found to be characterized by a sigmoid curve, with a threshold value, above which the permeability markedly increased. A correlation was found between cell membrane permeabilization and cell inactivation. Both heat-induced permeabilization and heat cytotoxicity were more pronounced in the transformed cells, as compared to their untransformed counterparts. The temperature-dependent permeabilization was more effective in the presence of the ionophore amphotericin B. The data suggest that heat-induced lesion in the cell membrane has a major role in hyperthermia cytotoxicity.

Amphotericin B↗
PubMed1976

[Radiosensitive mutants of Escherichia coli with disrupted cell membrane permeability].

Membrane proteins and cell permeability of Escherichia coli B/r and different substrains of B/r containing mutations of loci uvrB, exrA, lon and suppressors of that mutations were studied. Membrane proteins were found to be modified only in E. coli B/r exrA. The content of 40 000--70 000 D polypeptides was increased and the content of 80 000--100 000 D polypeptides was decreased. Alteration of membrane proteins in E. coli B/r exrA was associated with the impaired permeability of cell membrane.

Cell Membrane Permeability↗
PubMedDate not supplied

Red blood cell membrane permeability of uremic and normal cells.

Although there is extensive evidence that uremic red cells are more fragile and less deformable than normal cells, there are essentially no data on red cell membrane permeability in uremia. We have obtained data for creatinine and uric acid permeability of red cells from normal and uremic individuals (dialysis patients on EPO). The creatinine permeability of uremic cells was significantly less than that of normal cells (p less than 0.02), while the uric acid permeability was significantly greater than that of normal cells (p less than 0.01). Experiments with uremic and normal cells suspended in phosphate buffered saline, and with normal cells suspended in uremic plasma, indicated that uremia alters both the red cell membrane and the plasma, with an unknown plasma constituent affecting the permeability.

Cell Membrane Permeability↗
PubMed1987

Determination of cell membrane permeability in concentrated cell ensembles.

The method of volume averaging is used to analyze the process of diffusion in concentrated cell ensembles in which significant resistance to mass transfer is caused by the cellular membrane. A general closure scheme is given that allows for direct theoretical prediction of effective diffusivities for any cellular geometry. Numerical results are presented for the classical parallelepiped arrangement used to model cellular systems, and these results are used in conjunction with experimental studies of concentrated cell ensembles to determine membrane permeabilities for solute diffusion in several cellular systems. Membrane permeabilities are compared with predictions from other models of diffusion in cellular systems.

Animals↗
PubMed1995

On age-related changes of cell membrane permeability in human buccal epithelium cells.

An original method for the determination of cell membrane permeability has been developed. Human buccal epithelium cells were treated with Indigo Carmine and the percentage of stained cells was determined. Employing this method, the age-related differences in properties of plasma membrane in cells of human buccal epithelium were demonstrated. In the group of aged donors the average level of cell stainability was higher than in the group of younger donors. These results demonstrate a decrease in outer cell membrane integrity with age.

Adult↗
PubMed1992

The effect of six sesquiterpenoid unsaturated dialdehydes on cell membrane permeability in human neuroblastoma SH-SY5Y cells.

The effect of six sesquiterpenes containing an unsaturated dialdehyde functionality, on cell membrane permeability in the human neuroblastoma cell line SH-SY5Y has been studied. The kinetics of the membrane leakage after addition of the sesquiterpenes were determined by measuring the efflux of radioactivity from cells preloaded with tritiated 2-deoxyglucose. The concentrations that gave 5% and 20% efflux of radioactivity as compared with control cells (EC5 and EC20) were determined for each compound. In spite of the structural similarities between the compounds, the effects on cell membrane permeability varied considerably. EC20 for polygodial, which is the most active compound, is 2.5 microM after 20-min incubation, but no leakage could be determined for merulidial even at concentrations as high as 4 mM. Rather, this compound seems to stabilize or fix the cell membrane and a lower efflux of radioactivity was observed as compared to the control cells. A quantitative structure-activity relationship analysis for the five active compounds showed a good correlation between the membrane leakage activity and certain chemical characteristics. Structural features strongly correlated with high activity were found to be: The geometry and the atomic charges of the unsaturated dialdehyde functionality, the dipole moment, the energy difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital and the lipophilicity.

Aldehydes↗
PubMed1995

Dynamics of cell membrane permeability changes at supraphysiological temperatures.

A quantitative fluorescent microscopy system was developed to characterize, in real time, the effects of supraphysiological temperatures between 37 degrees and 70 degrees C on the plasma membrane of mouse 3T3 fibroblasts and isolated rat skeletal muscle cells. Membrane permeability was assessed by monitoring the leakage as a function of time of the fluorescent membrane integrity probe calcein. The kinetics of dye leakage increased with increasing temperature in both the 3T3 fibroblasts and the skeletal muscle cells. Analytical solutions derived from a two-compartment transport model showed that, for both cell types, a time-dependent permeability assumption provided a statistically better fit of the model predictions to the data than a constant permeability assumption. This finding suggests that the plasma membrane integrity is continuously being compromised while cells are subjected to supraphysiological temperatures.

3T3 Cells↗
PubMed1992

Modulation of membrane permeability, cell proliferation and cytotoxicity of antitumor agents by external ATP in mouse tumor cells.

External ATP causes a remarkable change in the passive permeability of the plasma membrane in several types of transformed cells. When mouse melanoma cells, Clone-M3, were exposed to ATP in Tris-buffered saline, a great increase in the passive permeability was induced within several minutes. Longer exposure of Clone-M3 cells to external ATP led to a decrease in cell viability. Similar results were obtained with Ehrlich ascites cells, but none of these ATP effects were noted in untransformed cells such as NIH 3T3 cells or BALB/c mouse embryonic fibroblasts. The in vitro cytotoxic effects of antitumor agents (5-fluorouracil, adriamycin, mitomycin C and nimustine hydrochloride) against Clone-M3 cells were additively potentiated by treatment with external ATP, which also synergistically enhanced the cytotoxicity of vincristine. However, the effects of these drugs on mouse embryonic fibroblasts were not modulated by ATP. These results suggest that ATP-treatment is a useful means of enhancing a selective toxicity for tumor cells.

3T3 Cells↗
PubMed1974

Red cell membrane permeability deduced from bulk diffusion coefficients.

The permeability coefficients of dog red cell membrane to tritiated water and to a series of[(14)C]amides have been deduced from bulk diffusion measurements through a "tissue" composed of packed red cells. Red cells were packed by centrifugation inside polyethylene tubing. The red cell column was pulsed at one end with radiolabeled solute and diffusion was allowed to proceed for several hours. The distribution of radioactivity along the red cell column was measured by sequential slicing and counting, and the diffusion coefficient was determined by a simple plotting technique, assuming a one-dimensional diffusional model. In order to derive the red cell membrane permeability coefficient from the bulk diffusion coefficient, the red cells were assumed to be packed in a regular manner approximating closely spaced parallelopipeds. The local steady-state diffusional flux was idealized as a one-dimensional intracellular pathway in parallel with a one-dimensional extracellular pathway with solute exchange occurring within the series pathway and between the pathways. The diffusion coefficients in the intracellular and extracellular pathways were estimated from bulk diffusion measurements through concentrated hemoglobin solutions and plasma, respectively; while the volume of the extracellular pathway was determined using radiolabeled sucrose. The membrane permeability coefficients were in satisfactory agreement with the data of Sha'afi, R. I., C. M. Gary-Bobo, and A. K. Solomon (1971. J. Gen. Physiol. 58:238) obtained by a rapid-reaction technique. The method is simple and particularly well suited for rapidly permeating solutes.

Amides↗
PubMed1982

The effect of cetiedil on red cell membrane permeability.

We report the effects of cetiedil, a new antisickling agent, on red cell membrane permeability. With fresh red cells containing normal levels of intracellular ATP, cetiedil increases membrane permeability to both sodium and potassium. With drug concentrations from 100 to 500 microM, net sodium gain exceeds net potassium loss, and the cells quickly swell. Changes are identical with normal and sickle red cells. Membrane permeability returns to normal after washing the cells in buffer free of cetiedil. In the absence of phosphate, ouabain potentiates the cetiedil effect. With external phosphate present, the effect of cetiedil is also enhanced, but ouabain is without effect. Our findings support the idea that the antisickling effect of cetiedil observed in vitro is secondary to cell swelling.

Adenosine Triphosphate↗
PubMed1985

Adenovirus-dependent increase in cell membrane permeability.

When KB cells were labeled with either 51Cr (1 microCi/ml) or [35S]methionine (5 microCi/ml) and treated with 10 micrograms/ml of adenovirus type 2 (Ad2) at pH 6.0 for 60 min at 37 degrees C, about 25% of the cell-associated 51Cr and 5% of the [35S]methionine were released into the medium. The 51Cr was mainly associated with molecules of 1500 Da or less. When KB cells were labeled with either [3H] choline, alpha-[3H]aminobutyric acid, or [3H]deoxy-2-fluoro-D-glucose and exposed to Ad2, these molecules were released in amounts much higher than 51Cr. The Ad2-dependent release of choline was found to be dependent on Ad2 concentration, with maximum release (nearly 60%) at 10 micrograms/ml of Ad2, on the length of the incubation with Ad2, with maximum release at about 90 min, and on the medium pH with maximum activity at pH 6.0 to 6.5. Greater than 95% of the choline released was water-soluble and identified as choline phosphate. Less than 5% of the choline released was associated with lipids, and none was released as a phospholipid vesicle or micelle. The ability of Ad2 to release choline was abolished by incubating Ad2 for 10 min at 45 degrees C, whereas the binding of Ad2 to the cells was not affected. Fetal calf serum also blocked Ad2-dependent choline release.

Adenoviridae↗
PubMed1994

Bacterial translocation, intestinal ultrastructure and cell membrane permeability early after major liver resection in the rat.

The process and route of bacterial translocation from the gut after major liver resection remain unclear. In the present study enteric bacterial translocation, enterocyte ultrastructure in the ileum and colon, the process and route of bacterial invasion and the permeability of the cell membrane system and blood-tissue barrier were evaluated in rats receiving sham operation, and 70 or 90 per cent hepatectomy. The incidence of bacterial translocation to mesenteric lymph nodes was 80-100 per cent in rats 6 h after 70 per cent and 2-4 h after 90 per cent hepatectomy, and 80-100 per cent to the systemic circulation 2-4 h after 90 per cent hepatectomy but only 20 per cent to the portal vein. An increase in bacterial adherence to the intestinal surface, damage to the permeability of the cell membrane system and blood-tissue barrier, and pathological alterations in the ileum and colon developed, correlating with the extent of liver removed and the time that had passed after hepatectomy. Most translocating bacteria appeared in morphologically intact enterocytes with increased membrane permeability, in antigen-presenting cells and in submucosal lymphatics, but some bacteria were also seen within damaged enterocytes 4h after 90 per cent hepatectomy. These results indicate that altered permeability of the cell membrane system may be one of the earliest characteristics of challenged enterocytes, and that enteric bacteria translocate through both morphologically normal and abnormal enterocytes. Translocation occurred mainly into the lymphatics, bacteria either being 'carried' by antigen-presenting cells or entering by active invasion.

Animals↗
PubMedDate not supplied

[Evaluation of cell membrane permeability for Ca2+ and adenylate cyclase in sheep peripheral blood cells, exposed to low doses of radiation].

Chronic irradiation of sheep with doses of 2.6 and 12.9 mC.kg was characterized by the modification of the adenylatecyclase activity and Ca2+ permeability of plasma membrane in cells of the peripheric blood, with no changes in the clinical and hematological indicators. The observed effects are assumed to result from structural and dynamic variations in the lipids of membranes.

Adenylyl Cyclases↗
PubMed1978

Increased cell membrane permeability to Na+ and K+ induced by thyroid hormone in rat skeletal muscle.

Thyroid hormone (T3) increased Na+ dependent respiration accompanied by an increase in NaK-ATPase activity. Administration of T3 increased intracellular K+ concentration and Na/K ratio in thyroidectomized rats, and the Na+ efflux rate constant incubated in oxygenized Na+, K+-Ringers in euthyroid rats. However, the magnitude of the changes in intracellular K+ concentration was modest or invisible in comparison to the changes in QO2(t) and NaK-ATPase activity. The Na+ and K+ efflux rate constants in K+-free +ouabain Ringers were increased by T3 in both thyroidectomized and euthyroid rats. Thus, thyroid hormone stimulates not only Na pump but also the permeability of cell membrane to Na+ and K+. The both effects might contribute to the thyroid thermogenesis.

Adenosine Triphosphatases↗
PubMed1998

Genetic engineering of proteins with cell membrane permeability.

The discovery of methods for generating proteins with inherent cell membrane-translocating activity will expand our ability to study and manipulate various intracellular processes in living systems. We report a method to engineer proteins with cell-membrane permeability. After a 12-amino acid residue membrane-translocating sequence (MTS) was fused to the C-terminus of glutathione S-transferase (GST), the resultant GST-MTS fusion proteins were efficiently imported into NIH 3T3 fibroblasts and other cells. To explore the applicability of this nondestructive import method to the study of intracellular processes, a 41-kDa GST-Grb2SH2-MTS fusion protein containing the Grb2 SH2 domain was tested for its effect on the epidermal growth factor (EGF)-stimulated signaling pathway. This fusion protein entered cells, formed a complex with phosphorylated EGF receptor (EGFR), and inhibited EGF-induced EGFR-Grb2 association and mitogen-activated protein kinase activation.

3T3 Cells↗
PubMedDate not supplied

Effect of storage time on red blood cell membrane permeability to creatinine and uric acid.

Although there is considerable evidence that blood storage affects red blood cell viability, deformability, and geometry, available data on the effect of blood storage on solute transport across the red blood cell membrane are highly limited. The authors used a stirred ultrafiltration device, with direct cell-free fluid sampling through a semipermeable ultrafiltration membrane, to obtain accurate data on red blood cell membrane permeability to both creatinine and uric acid. Results for influx and efflux experiments can be adequately explained by a passive transport mechanism. The red blood cell membrane permeability to uric acid increased substantially during storage, whereas trends in creatinine permeability were less clear and suggested possible differences between solute efflux and influx experiments. These results provide important insights into the physical and biochemical changes that occur in the red blood cell membrane during storage and also have important implications for analyses of solute removal in hemodialysis.

Blood Preservation↗